title: Predicting transition to chronic pain.
abstract: OBJECTIVE
  Most individuals who develop pain following an inciting event will return to a healthy state as the injury heals. However, a small percentage continue to suffer, that is, transition to chronic pain. Chronic pain may persist for years and is accompanied by cognitive abnormalities, as well as diminished quality of life. In animals, persistent pain is characterized by peripheral and spinal cord reorganization, and recent evidence in humans also indicates cortical reorganization. Yet, despite more than 30 years of research, there is little agreement on the neural mechanisms that mediate the transition from acute to chronic pain.
  
  
  RESULTS
  In a longitudinal brain-imaging study, individuals who developed an intense back pain episode were followed over a 1-year period, during which pain and brain parameters were collected repeatedly. A smaller number of healthy individuals and chronic back pain patients were also studied concomitantly, as positive and negative controls. At the time of entry into the study, strength of synchrony between the medial prefrontal cortex and nucleus accumbens (i.e. functional connectivity) was predictive (>80% accuracy) of individuals who subsequently transition to chronicity 1 year later.
  
  
  CONCLUSIONS
  Properties of the brain's emotional learning circuitry predict the transition to chronic pain. The involvement of this circuitry in pain remains mostly unexplored. Future human and animal model studies are necessary to unravel underlying mechanisms driving pain chronicity, with the potential of advancing novel therapeutics for preventing pain chronification.
authors.affiliation: Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, USA. a-apkarian@northwestern.edu
authors.forename: A Vania
authors.initials: AV
authors.lastname: Apkarian
authors.forename: Marwan N
authors.initials: MN
authors.lastname: Baliki
authors.forename: Melissa A
authors.initials: MA
authors.lastname: Farmer
mesh_terms: D001921:Brain / Q000473:pathology*; D059350:Chronic Pain / Q000175:diagnosis / Q000209:etiology / Q000523:psychology; D006801:Humans; D059906:Neuroimaging; D010147:Pain Measurement; D011237:Predictive Value of Tests; D012307:Risk Factors